Category: Respiratory System

Here is what we have learned from Introduction to the Respiratory System: The entire process of respiration includes ventilation, external respiration, transport of gases, internal respiration, and cellular respiration. The three pressures responsible for pulmonary ventilation are atmospheric pressure, intraalveolar pressure, and intrapleural pressure. A spirometer is used to measure respiratory volumes and capacities. These measurements…

The two lungs, which contain all the components of the bronchial tree beyond the primary bronchi, occupy most of the space in the thoracic cavity. The lungs are soft and spongy because they are mostly air spaces surrounded by the alveolar cells and elastic connective tissue. They are separated from each other by the mediastinum, which contains the heart.…

In the mediastinum, at the level of the fifth thoracic vertebra, the trachea divides into the right and left primary bronchi. The bronchi branch into smaller and smaller passageways until they terminate in tiny air sacs called alveoli. The cartilage and mucous membrane of the primary bronchi are similar to that in the trachea. As the branching continues through the bronchial tree, the amount of hyaline…

The trachea, commonly called the windpipe, is the main airway to the lungs. It divides into the right and left bronchi at the level of the fifth thoracic vertebra, channeling air to the right or left lung. The hyaline cartilage in the tracheal wall provides support and keeps the trachea from collapsing. The posterior soft tissue allows for expansion of the esophagus, which is immediately posterior…

The larynx, commonly called the voice box or glottis, is the passageway for air between the pharynx above and the trachea below. It extends from the fourth to the sixth vertebral levels. The larynx is often divided into three sections: sublarynx, larynx, and supralarynx. It is formed by nine cartilages that are connected to each other by muscles and ligaments. The larynx plays…

The pharynx, commonly called the throat, is a passageway that extends from the base of the skull to the level of the sixth cervical vertebra. It serves both the respiratory and digestive systems by receiving air from the nasal cavity and air, food, and water from the oral cavity. Inferiorly, it opens into the larynx and esophagus. The pharynx is divided into three regions according to location: the nasopharynx, the oropharynx, and the laryngopharynx (hypopharynx). The nasopharynx…

Paranasal sinuses are air-filled cavities in the frontal, maxilae, ethmoid, and sphenoid bones. These sinuses, which have the same names as the bones in which they are located, surround the nasal cavity and open into it. They function to reduce the weight of the skull, to produce mucus, and to influence voice quality by acting as resonating chambers.

The framework of the nose consists of bone and cartilage. Two small nasal bones and extensions of the maxillae form the bridge of the nose, which is the bony portion. The remainder of the framework is cartilage and is the flexible portion. Connective tissue and skin cover the framework. Air enters the nasal cavity from the outside through two openings: the nostrils or external nares. The openings from the nasal…

The respiratory conducting passages are divided into the upper respiratory tract and the lower respiratory tract. The upper respiratory tract includes the nose, pharynx, and larynx. The lower respiratory tract consists of the trachea, bronchial tree, and lungs. These tracts open to the outside and are lined with mucous membranes. In some regions, the membrane has hairs that help filter the air. Other regions may have cilia to…

Under normal conditions, the average adult takes 12 to 15 breaths a minute. A breath is one complete respiratory cycle that consists of one inspiration and one expiration. An instrument called a spirometer is used to measure the volume of air that moves into and out of the lungs, and the process of taking the measurements is called spirometry. Respiratory (pulmonary) volumes are an…